Befriend - as in make a friend, or even a girlfriend if that's what you want - is not something that you can choose. It's a potential outcome from something that you can choose to do or not.. Which is interact in the first place.
If you choose to interact then whatever you do don't start with "Hello" that's just odd. Make a comment about something present like the bus/train/weather, and say with "Isn't it?" at the end. At that point you'll need to gauge her reaction, response, and body language - if she's not interested then that's the end of the befriending and you must stop. If it's good then make another and comment and talk about whatever you want to and see if she wants to get a coffee sometime.
One more comment, you need to be totally clear about your intentions in your own mind and whatever they are they need to be communicated to her reasonably clearly, or one or both of you will just be disappointed.